TECHNOLOGIES & APPLICATIONS

COLD-CATHODE HIGH-CURRENT LOW-PRESSURE
SPARK SWITCHES (PSEUDOSPARK SWITCHES)

Purpose

Pseudospark switches have been developed at the Institute of High Current Electronics in collaboration with the Scientific Production Company "Pulsed Technology Ltd." (Ryazan, Russia), based on fundamental studies in gas discharge physics.

These devices are intended for switching high-current, high-voltage pulses on the nanosecond and microsecond scales and can be used as key units in power supplies for lasers, in plasma focusing systems, in water purification and gas scrubbing systems, in medical apparatus, in geology, oil output, etc.

Outline and technical and economic characteristics

A family of pseudospark switches is illustrated by the photograph. The devices are produced in sealed-off form and have a ceramic case making them mechanically strong. The working gas pressure in this type of switch is provided by a built-in hydrogen generator. The principle of operation of the devices is based on a low-pressure discharge initiated in a hollow-electrode system.

The use of this type of discharge together with original designs of the electrodes and trigger units has made it possible to achieve the unique characteristics of the devices as follows:

rise rate of the switched current up to 10¹² A/s
jitter ~ 1 ns
total charge the device can switch before failure up to 10⁶ C

Schematic of the switch TDI1-150k/25.
1 - ceramic chamber, 2 - main cathode, 3 - main anode, 4 - cathode flange, 5 - anode flange, 6 - H₂-reservoir heater, 7 - upper flange, 8 - baffle, 9 - semiconductor cylinder of the trigger unit, 10 - multi-point contact, 11 - terminal of the cylinder, 12 - cathode cavity.

Schematic of the switch TPI1-10k/50.
1 - ring anode of the auxiliary glow discharge, 2 - hollow cathode of the auxiliary glow discharge, 3 - main cathode, 4 - intermediate (gradient) electrode, 5 - main anode, 6 - potential anode.

About ten types of pseudospark gap capable of switching currents ranging from 100 A to 150 kA at a voltage of up to 100 kV.

The principal parameters of the devices
Switch type	Anode voltage, kV	Peak anode current, kA	Average current, A	Dimensions (diameter x height), mm	Total charge transfer (min), C S Q, К	Pulse repetition rate, kHz
TDI1-50k/16	5÷16	50	0.15	50x52	10⁵	0.1
TDI1-50k/25	5÷25	50	0.25	98x80	2x10⁵	0.1
TDI1-50k/50	5÷50	50	0.25	98x88	2x10⁵	0.1
TDI1-150k/25	5÷25	150	0.5	118x50	5x10⁵	0.1
TPI1-0.2k/12	1÷12	0.2	0.03	25x22	10⁶	2.5
TPI1-1k/20	1÷20	0.2	0.05	25x22	10⁶	2.0
TPI3-10k/25	1÷25	10	0.2	25x22	10⁶	1.0
TPI1-10k/25	1÷25	10	0.5	25x22	10⁶	2.0
TPI1-10k/50	1÷50	10	0.3	25x22	10⁶	2.0

Principal advantages

As distinct from spark and vacuum switches and from pulsed power hydrogen thyratrons, the pseudospark switches offer the advantages as follows:

the capability of switching current pulses of both positive and negative polarity
the ability to operate at both positive and negative voltage applied to the anode
low jitter operation
long lifetime
comparatively low cost
simple design

Analogs

The devices most closely approaching by their parameters the pseudospark switches are pulsed power hydrogen thyratrons and grounded-grid thyratrons commercially produced by the EEV (UK) and EG&G (USA) companies. The latter, however, have a substantially higher cost.

Patenting

The pseudospark switches are protected by authorship certificates and patents of the Russian Federation.

Development phase

The pseudospark switches are produced in about ten versions. The study of low-pressure discharges is being continued and development work aimed at improving the characteristics of the devices is being performed.

At present this work is supported by the NATO Science for Peace Programme (title: Investigation of pseudospark discharge and development of a novel type of high-current switching device on this basis. Project number SfP 972580).

This project is organized as a close collaboration between the High Current Electronic Institute (Tomsk, Russia), the University of Erlangen (Erlangen, Germany), and the Scientific Production Company "Pulsed Technology Ltd." (Ryazan, Russia).

End-user

Dr. V.D. Bochkov
Scientific Production Company "Pulsed Technology Ltd."
Yablochkova str., 5 390023 Ryazan Russia
Phone: (4912) 24-05-19 Fax: (4912) 24-92-17
E-mail: info@pulsetech.ru, E-mail: pulsetech@mail.ru

Suggestions for collaboration

to perform joint work on studying the processes occurring in low-pressure gas discharges;
to seek for specialist advices in choosing the type of switching units for pulsed power systems;
to market the pseudospark switches and to adapt them to user's systems.

For further information please contact:

Yury D. Korolev,
Professor, Dr. Sci. (Phys. & Math.), Laboratory Head

Phone: (3822) 49 19 71
Fax: (3822) 49 24 10

E-mail: korolev@lnp.hcei.tsc.ru

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